SD Memory Card - Microcontroller Interface

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Hello,

I don't have a particular project in mind, but it seems like having
512+MB of memory at my disposal for microcontroller projects would be
quite amazing.  From a few of the posts I've read, and the limited
specs I could find, it seems like Secure Digital (SD) memory cards
allow for an SPI interface (serial) and run anywhere from 0-25Mhz.
(I've interfaced to CompactFlash cards and Cardbus, and SPI seems much
easier, in concept)

But a few of the articles I found about SD cards briefly talked about
their security features and the need to pay the "Secure Digital People"
for specs on the device and perhaps even some proprietary information
on how to talk to the chip such that it will actually store and
retrieve data.  Is this correct?!

If there is any known work around, I would love to hear it.  I guess
that brings me to my two questions, shown below:

1. What is the pinout for the SD card?
2. What are the protocol specs to address the SD card, put it in
read/write mode, and then access data? (a PDF datasheet would be
helpful here)

I'm sure if there was a simple way to tap into the SD card, only
requiring the small number of standard SPI pins, microcontroller
projects with high storage capabilities would spring up everywhere
since the pin count is so small and the memory sizes keep getting
larger by the day. :)
Thanks for your help!

 Best Regards,
    Adam Kumpf


Re: SD Memory Card - Microcontroller Interface

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Yeah, you gotta pay. Skip SD. Go with MMC. Same benefits, and you can
still use SPI. The only down side is that MMC is less plentiful these days.

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Re: SD Memory Card - Microcontroller Interface

|
|| Hello,
||
|| I don't have a particular project in mind, but it seems like having
|| 512+MB of memory at my disposal for microcontroller projects would be
|| quite amazing.  From a few of the posts I've read, and the limited
|| specs I could find, it seems like Secure Digital (SD) memory cards
|| allow for an SPI interface (serial) and run anywhere from 0-25Mhz.
|| (I've interfaced to CompactFlash cards and Cardbus, and SPI seems much
|| easier, in concept)
||
|| But a few of the articles I found about SD cards briefly talked about
|| their security features and the need to pay the "Secure Digital People"
|| for specs on the device and perhaps even some proprietary information
|| on how to talk to the chip such that it will actually store and
|| retrieve data.  Is this correct?!
|
| Yeah, you gotta pay. Skip SD. Go with MMC. Same benefits, and you can
| still use SPI. The only down side is that MMC is less plentiful these
days.

I've recently purchased the MMC-RTC-1 board from Bipom, for use as data
acquisition on a weather station:

http://www.bipom.com/periph_boards.shtm

I'm still waiting for my order to either arrive in the mail or show up on my
credit card bill.  All that they sent me was a blank email as an order
confirmation.  Not exactly the best system.

Also, I didn't purchase an MMC card from them in hopes that I can buy one
cheaper elsewhere, but I probably should have looked into that first.

Goodluck.

--
MT

To reply directly, take every occurrence of the letter 'y' out of my
address.



Re: SD Memory Card - Microcontroller Interface

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days.

And you may well find that your MMC logic works with the SD card, which
are likely to be downward compatible.  You won't have SD features, but
you won't pay the standards tax, either.

But there may be some issues requiring you to format the card
as an MMC device.

Rufus



Re: SD Memory Card - Microcontroller Interface
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Go to Sandisk's website, and get the MultiMediaCard spec in the OEM
section.  Develop your software against the MMC spec.  If your
software follows the MMC spec, it will talk to an SD card without
changes.  You don't need to know anything about the security features,
and you don't need the SD card spec.  The only difference will be that
you'll need an SD-compatible slot, since the SD card is thicker.

--
John W. Temples, III

Re: SD Memory Card - Microcontroller Interface

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http://www.sandisk.com/pdf/oem/ProdManualSDCardv1.9.pdf Sandisk SD card
product manual
http://www.sandisk.com/pdf/oem/ProdManualminiSDv1.1.pdf MiniSD card
http://www.sandisk.com/download/Product%20Manuals/Product%20ManualSDCardv1.7.pdf
  Older SD card
specs

Using SDCard and SDIO with the Intel® PXA250 MMC Controller Application Note
http://www.intel.com/design/pca/applicationsprocessors/applnots/278533-001.htm
Toshiba SD card specification
http://i.cmpnet.com/chipcenter/memory/images/prod055.pdf

You can order the spec (version 3.31) for US$500 from www.mmca.org
Version 4 has been released.

These links may also be of some use.
http://instruct1.cit.cornell.edu/courses/ee476/FinalProjects/s2000/peterdan/final.htm
http://homepage.ntlworld.com/seanellis/mmcserial.htm
http://www.positron.org/projects/juicebox /
http://www.compsys1.com/workbench/On_top_of_the_Bench/MMC_Project/mmc_project.html


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